Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C55/00—Shaping by stretching, e.g. drawing through a die; Apparatus therefor
  • B29C55/02—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets
  • B29C55/10—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets multiaxial
  • B29C55/12—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets multiaxial biaxial
  • B29C55/14—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets multiaxial biaxial successively
  • B29C55/143—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets multiaxial biaxial successively firstly parallel to the direction of feed and then transversely thereto
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
  • B32B27/08—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/18—Layered products comprising a layer of synthetic resin characterised by the use of special additives
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2023/00—Use of polyalkenes or derivatives thereof as moulding material
  • B29K2023/10—Polymers of propylene
  • B29K2023/12—PP, i.e. polypropylene
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2995/00—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds
  • B29K2995/0037—Other properties
  • B29K2995/0049—Heat shrinkable
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2307/00—Properties of the layers or laminate
  • B32B2307/40—Properties of the layers or laminate having particular optical properties
  • B32B2307/412—Transparent
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2307/00—Properties of the layers or laminate
  • B32B2307/50—Properties of the layers or laminate having particular mechanical properties
  • B32B2307/51—Elastic
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2307/00—Properties of the layers or laminate
  • B32B2307/50—Properties of the layers or laminate having particular mechanical properties
  • B32B2307/54—Yield strength; Tensile strength
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2307/00—Properties of the layers or laminate
  • B32B2307/70—Other properties
  • B32B2307/732—Dimensional properties
  • B32B2307/734—Dimensional stability
  • B32B2307/736—Shrinkable
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2323/00—Polyalkenes
  • B32B2323/10—Polypropylene
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S428/00—Stock material or miscellaneous articles
  • Y10S428/91—Product with molecular orientation
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/24—Structurally defined web or sheet [e.g., overall dimension, etc.]
  • Y10T428/24942—Structurally defined web or sheet [e.g., overall dimension, etc.] including components having same physical characteristic in differing degree
  • Y10T428/2495—Thickness [relative or absolute]
  • Y10T428/24967—Absolute thicknesses specified
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/28—Web or sheet containing structurally defined element or component and having an adhesive outermost layer
  • Y10T428/2813—Heat or solvent activated or sealable
  • Y10T428/2817—Heat sealable
  • Y10T428/2826—Synthetic resin or polymer
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/31504—Composite [nonstructural laminate]
  • Y10T428/31855—Of addition polymer from unsaturated monomers
  • Y10T428/31909—Next to second addition polymer from unsaturated monomers
  • Y10T428/31913—Monoolefin polymer
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/31504—Composite [nonstructural laminate]
  • Y10T428/31855—Of addition polymer from unsaturated monomers
  • Y10T428/31909—Next to second addition polymer from unsaturated monomers
  • Y10T428/31924—Including polyene monomers

Definitions

• the present invention relates to a transparent shrinkable film comprising a base layer containing a mixture of polypropylene and hydrocarbon resin.
• the invention further relates to a method for producing such a film and its use as shrink labels.
• the films for this application are e.g. B. from polyethylene, polybutylene, polystyrene, polyethylene-polypropylene copolymers, ethylene-vinyl acetate copolymers, various blends, but in particular from polyvinyl chloride.
• the films are generally biaxially stretch-oriented, which, for. B.
• the shrink films are also z. B. printed in reverse printing and then glued or welded to a tube. Thanks to the controlled cross-shrinkage, the tube is fixed in the shrinking furnace and free of creases around the packaging unit.
• the label is applied mechanically with the help of brushes or alternatively manually.
• a disadvantage of the all-round PVC labels is the high price, which mainly results from the high density of 1.39 kg / dm3, which is approx. 50% higher than that of e.g. B. PP, to name, also exist Pro problems with corrosion of the manufacturing and processing units (cf. EP-A-0 233 400).
• Shrink label films based on polyolefin consist mainly of blends based on homopolymers, copolymers and terpolymers. In order to achieve the required shrinkage properties, the films are stretched biaxially in the bubble or stenter process.
• a biaxially oriented film is produced using the two-stage process.
• the film is annealed between the longitudinal stretching and the transverse stretching in an additional step at an elevated temperature (approx. 130 ° C.).
• the annealing time is 2 to 180 s.
• a relatively complex and expensive unit must be arranged between the longitudinal and transverse stretching in this process, because with a tempering time of e.g. B. 60 s and a machine speed of 200 m / min would require a furnace length of 200 m.
• the method is therefore unsuitable from a process engineering point of view for the production of foils using the methods customary today.
• the film has mechanical properties that can be improved.
• the object of the present invention was to develop a transparent, easily glued and easily shrinkable multilayer film for wrap-around labels based on polypropylene, which has very good optical and mechanical properties and thus above all enables economic advantages over films according to the prior art.
• a base layer comprises 60 to 95% by weight of a propylene polymer and 5 to 40% by weight of a hydrogenated hydrocarbon resin with a softening point in the range from 60 to 125 ° C contains, where the percentages are based on the total weight of the mixture, and that on both surfaces of the base layer outer layers of polypropylene are arranged containing 60 to 100 wt .-% of a propylene polymer and 0 to 40 wt .-% of a hydrogenated hydrocarbon resin with a Softening point in the range from 90 to 145 ° C, the percentages being based on the total weight of the outer layers.
• the propylene polymer of the base layer is an isotactic polypropylene with an n-heptane-soluble fraction of 15% by weight or less, with isotactic polypropylenes with an n-heptane-soluble fraction of 2 to 6% by weight being particularly preferred.
• Suitable propylene polymers expediently have a melt flow index of 0.5 g / 10 min to 8 g / 10 min at 230 ° C. and 2.16 kp load (determined in accordance with DIN 53 735), in particular from 1.5 g / 10 min to 4 g / 10 min.
• the propylene polymer of the cover layers is an isotactic polypropylene with an n-heptane-soluble content of 15% by weight or less, with isotactic polypropylenes with an n-heptane-soluble content of 2 to 6% by weight being particularly preferred.
• the melt flow index of the propylene polymer of the top layer should advantageously be higher be that of the propylene polymer for the base layer.
• Propylene polymers suitable for the cover layers should therefore have a melt flow index in the range from 5 to 20 g / 10 min.
• the hydrocarbon resin which is also present in the base layer of the film according to the invention is a low molecular weight synthetic resin which has a softening point in the preferred range from 70 to 90 ° C., determined in accordance with ASTM-E 28.
• Such hydrocarbon resins are usually made from resin-forming compounds such as styrene, methyl styrene, vinyl toluene, indene, pentadiene, cyclopentadiene and the like. ⁇ . formed.
• hydrogenated resins in particular hydrogenated cyclopentadiene resins, are particularly preferred.
• the Saybold color number (according to ASTM D 158) is greater than 20, preferably greater than 25.
• the resin contained in the cover layers in the amounts indicated can in principle be the same resin as is contained in the base layer, but has been shown that resins which have a softening point at higher temperatures, preferably in the range from 110 ° C. to 135 ° C., can advantageously be used for the cover layers.
• the chemical composition of such resins is the same as that of the softening point resins in a lower temperature range.
• the cover layers preferably additionally contain an inorganic or organic antiblocking agent.
• Suitable antiblocking agents are inorganic additives, e.g. B. silicon dioxide and calcium carbonate or the like. It is essential for the antiblocking agent that the average particle size is between 1.5 and 3 ⁇ m and its form factor is ⁇ 3.
• the refractive index of the antiblocking agents is between 1.4 and 1.6. SiO2 and calcium carbonate are preferred as antiblocking agents.
• the amount added is 0.1 to 0.5% by weight.
• the form factor of the antiblocking agent is the ratio of the largest surface area to the thickness of the particles. According to this definition, a cube-shaped antiblocking agent has e.g. B. a form factor of 1.
• the layers can contain suitable active ingredient components in each case in effective amounts, preferably antistatic agents and / or lubricants.
• Preferred antistatic agents are essentially straight-chain and saturated aliphatic, tertiary amines with an aliphatic radical having 10 to 20 carbon atoms, which are substituted by 2-hydroxyalkyl (C1-C4) groups, including N, N-bis (2-hydroxyethyl) -alkylamines with C10-C20, preferably C12-C18, are particularly suitable as alkyl groups.
• the effective amount of antistatic is in the range of 0.05 to 1% by weight based on the layer.
• top layer with 0.1 to 0.7% by weight of an N, N-bis-ethoxyalkylamine with an aliphatic radical with 10 to 20 carbon atoms.
• lubricants are higher aliphatic acid amides, higher aliphatic acid esters, waxes and metal soaps as well as polydimethylsiloxane.
• the effective amount of lubricant is in the range of 0.1 to 2% by weight based on the weight of the layer.
• higher aliphatic acid amides e.g. erucic acid amide
• very good results are achieved by adding polydimethylsiloxane to one or both top layers.
• the amount added is expediently in the range from 0.5 to 1.5% by weight, the viscosity of the polydimethylsiloxane being between 1,000 and 100,000 mm 2 / s.
• the thickness of the film according to the invention is in the range from 15 to 50 ⁇ m, preferably from 20 to 45 ⁇ m, the cover layers having a thickness of 0.5 to 1.0 ⁇ m.
• the film according to the invention described above with regard to its chemical composition is characterized in particular by very particularly desirable shrink properties. It has a shrinkage capacity of more than 20% at 90 ° C and more than 40% at 120 ° C in the transverse direction and at the same time Shrinkage capacity of less than 8% at 90 ° C and less than 16% at 120 ° C in the longitudinal direction, the percentages being based on the respective linear expansion of the film before the shrinking process.
• the specified shrinkage values were determined in a convection oven over a period of 15 minutes in accordance with DIN 406 34.
• the shrinkability of the film according to the invention is preferably in the range from 20 to 30% at 90 ° C. and from 40 to 60% at 120 ° C. and in the longitudinal direction in a range from 4 to 8% at 90 ° C. and at most 10 to 16% at 120 ° C, each based on the linear expansion of the film before the shrinking process.
• the film according to the invention also has particularly desirable mechanical properties.
• the modulus of elasticity is determined using a tension-stretching device from Zwick in Ulm-Einsingen of type 1445 in accordance with DIN 53 455.
• the film according to the invention then has a modulus of elasticity in the longitudinal direction of more than 2,000 N / mm2, preferably from 2,200 to 2,600 N / mm2, and an elastic modulus in the transverse direction of more than 4,000 N / mm2, preferably of 4 500 N / mm2 to 5 500 N / mm2.
• the shrink film according to the Er has a tensile strength in the longitudinal direction of more than 130 N / mm2, preferably in the range from 145 to 185 N / mm2, and in the transverse direction of more than 220 N / mm2, preferably in the range from 235 to 290 N / mm2.
• the optical properties of the film according to the invention are very excellent.
• the gloss value is in the range from 110 to 130, determined in accordance with DIN 67 530 or ASTM-D 523, and the haze of the film is less than 20%, preferably 10 to 15%, the haze of the film being based on ASTM-D 1003-52 is measured.
• a 4 ° perforated diaphragm a 1 ° slit diaphragm is used, and the haze in percent is given for four layers of film lying one above the other. The four positions were chosen because this enables the optimal measuring range to be used.
• the particularly high gloss value of the film according to the invention has a particularly effective advertising effect, and therefore the area of application of the film according to the invention can be seen above all where the labeling process (folding and shrinking) takes place automatically and is high on the product (can / bottle / dispenser) optical requirements are made.
• the object of the invention mentioned at the outset is also achieved by a method for producing the film described above.
• the process according to the invention consists in firstly producing a prefilm by means of extrusion or coextrusion in a slot die, which is then solidified on a chill roll and then stretched in the longitudinal and transverse directions is oriented.
• the conditions in the longitudinal stretching are selected so that the longitudinally stretched film is only slightly oriented.
• the prerequisites for achieving a high transverse shrinkage and a low longitudinal shrinkage are then particularly favorable.
• a common measure for assessing the extent of the orientation of the elongated film is the birefringence ⁇ n.
• the birefringence ⁇ n should preferably be ⁇ 8 ⁇ 10 ⁇ 3.
• the longitudinal stretching is carried out at a temperature of more than 140 ° C., preferably in the range from 145 to 165 ° C., and with a stretching ratio of less than 4.5, preferably in the range from 3 to 4.
• the transverse stretching temperature T q can be chosen to be much lower than is otherwise customary under these conditions and nevertheless very good process reliability is ensured.
• the transverse stretching is carried out at a temperature of less than 120 ° C., preferably less than 110 ° C.
• the stretch ratio in the transverse direction is more than 8, preferably in the range from 8.5 to 11.
• the film is at a temperature of 20 to 40 ° C below the Stretching temperature, in particular at a temperature below 110 ° C, preferably below 80 ° C, in the stretching frame, possibly slightly converging.
• the convergence during the fixing stage is preferably 5 to 15%.
• the top layers can be equipped with low molecular weight additives (carboxamides, N, N-bis-ethoxyalkylamines) without major technical problems. Evaporation problems and deposit problems in cross-stretching frames do not occur. Because of the process conditions according to the invention, there is also no disturbing resin evaporation.
• low molecular weight additives carboxyamides, N, N-bis-ethoxyalkylamines
• the printability or bondability of the film is achieved by one of the usual surface treatments before rolling up, e.g. B. flame treatment or electrical corona treatment.
• the procedure is expediently such that the film is passed between two conductor elements serving as electrodes, with such a high voltage, usually alternating voltage (approximately 10,000 V and 10,000 Hz.) Between the electrodes ), is designed that spray or corona discharges can take place.
• the air above the film surface is ionized by the spray or corona discharges and combines with the molecules on the film surface, so that polar inclusions arise in the essentially non-polar polymer matrix.
• treatment intensities are in the usual range. Treatment intensities of 38 to 42 mN / m are preferred.
• the film is preferably printed in reverse printing.
• the shrink film produced in this way has a combination of properties that make it particularly suitable for its intended use as a film for all-round labels. Their preferred area of application can be seen above all where the shape change of the can or bottle in the area of the labeling accounts for less than 25%.
• a multilayer film consisting of a base layer of 90 wt .-% isotactic polypropylene and 10 wt .-% hydrogenated cyclopentadiene resin with a softening temperature of 85 ° C and top layers of isotactic polypropylene, the 0.3 wt .-% of a CaCO3 with an average particle size of 2 ⁇ m and a form factor of 1.5% by weight of N, N-bis-ethoxyalkylamine ( (R) Armostat 300) and 0.7% by weight of polydimethylsiloxane (viscosity 30,000 cSt) were added the process steps of coextrusion, cooling, longitudinal stretching, Lateral stretching, fixation made.
• the total thickness of the film was 30 ⁇ m, the cover layers each being approximately 0.8 ⁇ m thick.
• the film produced in this way had the properties listed in the table (last line). Before being rolled up, the film was subjected to a corona treatment in order to ensure printability / stickability.
• the treatment intensity was 39 mN / m.
• the film according to the invention was compared with a PVC film, a film according to EP-A-0 171 733 and a polypropylene film produced under conditions similar to those according to the invention without the addition of resin.
• a comparison of the reported properties shows that the film according to the invention has proven to be superior to all known films, particularly with regard to the combination of properties sought in the task.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Laminated Bodies (AREA)
• Shaping By String And By Release Of Stress In Plastics And The Like (AREA)

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• 1988
  • 1988-06-25 DE DE19883821581 patent/DE3821581A1/de not_active Withdrawn
• 1989
  • 1989-06-16 EP EP19890110914 patent/EP0348749A3/fr not_active Withdrawn
  • 1989-06-26 JP JP1161011A patent/JPH0241245A/ja active Pending
  • 1989-06-26 US US07/371,300 patent/US5091237A/en not_active Expired - Fee Related

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